After hours of tweaking, trial, and error I think I've discovered my problem.
All things considered, after my last edit to my original post I figured it had to be some kind of INI problem.
So, what I did was I compared my MO INI files with the default INI files in my "\My Documents\my games\Skyrim" folder.
Looking at SkyrimPrefs.ini, the only significant differences between the two where I had absolutely no idea what they controlled were iTexMipMapMinimum and iTexMipMapSkip. In the default INI these values were both set to 0, whereas in the MO files they were set to 9 and 3, respectively.
I changed the MO INI values both to 0, and problem solved. I knew it right away because right after changing those 2 values to 0 the loadup dragon motif looked like it's supposed to. Sure enough, I can also now activate/deactivate my custom texture pack and notice the difference immediately upon loading a save.
As much as I am super glad that I've solved my problem, I'd still love to know why this happened, if anyone can provide comment on it. I have no idea why those values were set to 9 and 3 in the first place... I certainly didn't manually edit them in there. And it's my understanding that MO INI files are created from the defaults when you create a new profile, so if the default INI had the correct value, where the heck did the 9 and 3 come from? It also makes me wonder if any other of my INI settings are totally FUBAR from what they should be.
Also, why do these values affect texture loading like they did? I'm not knowledgeable enough in texture mapping, etc. to know exactly what these parameters control.
Anyway, thanks for reading, and hopefully if someone else runs across this issue this post will help solve the problem.
